1. Field of the Invention
The present invention relates to a shift register circuit. Further, the present invention relates to a display device in which a shift register circuit is formed over the same substrate as a pixel portion. Furthermore, the present invention relates to an electronic device including the display device.
2. Description of the Related Art
Display devices such as liquid crystal televisions are required to be manufactured at lower cost so as to be more widely used, so that development thereof have been conducted. In particular, a technique in which a driver circuit such as a scan line driver circuit is formed using a thin film transistor (TFT) over the same substrate as a pixel portion has been actively developed.
As an example of a driver circuit that can be formed over the same substrate as a pixel portion, there is a driver circuit having a configuration in which transistors having the same conductivity type (one conductivity type) are used in combination (for example, see Patent Document 1).